This document provides an overview of mandibular orthognathic procedures. It begins with an introduction to orthognathic surgery and the history of mandibular osteotomies. It then discusses anatomical and physiological considerations, timing of osteotomies, and various osteotomy techniques including vertical ramus, sagittal split, horizontal ramus, subapical, and total alveolar osteotomies. It also briefly touches on soft tissue changes and complications that can occur with mandibular osteotomies. The document is intended as a reference for various mandibular orthognathic procedures.

2. Presenter : Dr. Itrat Hussain
Moderator : Dr. Harsh Jain
Mandibular Orthognathic
Procedures

3. CONTENTS
1. Introduction
2. Historical aspects
3. Anatomical & physiological considerations of
mandibular osteotomies
4. Timing for the mandibular osteotomies
5. Mandibular osteotomies
6. Soft tissue changes after mandibular
osteotomies
7. Complications
8. References

4. INTRODUCTION
Orthognathic surgery is a process in
which dentofacial deformities and malocclusions
are corrected with orthodontics and surgical
operations of the facial skeleton, sometimes
combined with various soft tissue procedures.
The term orthognathic originates from the
Greek words orthos , ‘straight’, and gnathos ‘jaw’.
It is possible to correct, or
“straighten”, deformities separately in either the
maxilla or the mandible with many types
of surgical techniques or to do procedures
concurrently on both jaws.

5. HISTORY
Orthognathic surgery was originally developed in
the United States of America (Steinhäuser ).
The first mandibular osteotomy is considered to be
Hullihen´s procedure in 1849 to correct anterior
open bite & mandibular dento alveolar protrusion
with an intraoral osteotomy.
Osteotomy of the mandibular body for the
correction of mandibular horizontal excess was
performed by Vilray Blair (1890).

6. Berger (1897) described a condylar osteotomy for the
correction of prognathism.
Limberg in 1925 first reported the subcondylar
osteotomy as an extraoral technique, later it was
modified to the intraoral vertical subcondylar osteotomy.
A variation of the vertical subcondylar osteotomy was
suggested by Wassmund in 1927,which is similar to the
inverted –L-osteotomy.

7. Hofer in 1936 demonstrated an anterior
mandibular alveolar osteotomy to
advance anterior teeth in correction of a
mandibular dentoalveolar retrusion.
In 1954, Caldwell and Letterman
developed a Vertical Ramus Osteotomy
Technique, which had the advantage of
minimizing trauma to the inferior alveolar
neurovascular bundle.

8. The greatest development in osteotomies of the vertical ramus
is the sagittal split osteotomy credited to Obwegeser in 1955.
The major modifications in the osteotomies design were first
made by Dalpont in 1961.
This was further discussed by Hunsuck in 1968 in order to
decrease the trauma to overlying soft tissues.
Kent & Hinds in 1971 initially presented the use of single tooth
osteotomies of the mandible.
Macintosh closely followed with his description of the total
mandibular alveolar osteotomy in 1974.

9. Aesthetics
Function
Stability
AIMS OF MANDIBULAR OSTEOTOMIES

10. PRINCIPLES IN TREATING
MANDIBULAR DEFORMITIESPatient’s perception of the deformity and expectations
Surgeon’s recognition of the deformity
Complete physical examination, model surgery, cephalometric
analysis
Optimal treatment plan
Counseling of the patient
Informed consent

11. Vascular
structures
NervesMuscles
ANATOMICAL & PHYSIOLOGICAL CONSIDERATIONS
OF MANDIBULAR OSTEOTOMIES

12. VASCULAR STRUCTURES
Bell and Levy’s work {1970} demonstrated
that blood flow through the mandibular
periosteum could easily maintain a sufficient
blood supply to the teeth of a mobile segment,
even when the labial periosteum was degloved.
Subapical Osteotomies need to be carefully
planned to ensure as large a vascular pedicle as
possible.

13. The proximal segment of the vertical sub sigmoid
osteotomy maintains its blood supply through the
temporomandibular joint capsule and the
attachment of the lateral pterygoid muscle.
But the inferior tip of this fragment has undergone
vascular necrosis in some studies.
This led to the suggestion that fewer problems may
occur if the cut was made above the angle of the
mandible.

14. We should minimize the periosteal and
muscle attachment stripping on the medial
surface of the proximal fragment with either
the C or L osteotomy or any of their
variations.
The greater distance from the apices of the
teeth not only minimizes direct pulpal injury
but increases the vascular pedicle to the
mobile segment as well.

15. NERVES
In most cases in orthognathic surgery avoiding injury to
marginal mandibular branch of facial nerve is achieved
because soft tissue anatomy in patients undergoing the
surgery has not been disturbed by disease or trauma.
The course of the inferior alveolar nerve into the vertical
ramus and then through the body of the mandible makes
it extremely susceptible to damage from almost every
mandibular surgical procedure.
In most cases the surgeon’s main goal relative to this
nerve is only to minimize the trauma because its
avoidance is almost impossible.

16. MUSCLES
Orthognathic surgery affects muscles in
primarily two ways:
It changes the length of a muscle or it changes the
direction of muscle function.
The muscles commonly discussed in orthognathic
surgery of the mandible have been the muscles of
mastication and the suprahyoid group of muscles .

17. Evaluation of horizontal
osteotomy of vertical
ramus procedure following
correction of prognathism
found a superior
movement of the mandible
in the gonial region as well
as a downward and
backward movement at the
symphysis.
This change is attributed
to the forces of the
pterygomasseteric sling .

18. TIMING OF OSTEOTOMY
Union of epiphysis
& diaphysis

19. MANDIBULAR OSTEOTOMIES
VERTICAL RAMUS OSTEOTOMIES
BILATERAL SAGITTAL SPLIT OSTEOTOMY
HORIZONTAL RAMUS OSTEOTOMIES
SUB APICAL OSTEOTOMIES [segmental osteotomies]
TOTAL ALVEOLAR OSTEOTOMIES
HORIZONTAL OSTEOTOMY OF SYMPHYSIS/ GENIOPLASTY

20. VERTICAL SUBCONDYLAR OSTEOTOMIES
Indications:
Mandibular horizontal excess
Mandibular assymmetry
Painful TMJ
Incision: In the mucosa midway up the
anterior border of ramus to the first molar
area.
Exposure: Entire ramus is exposed
Advantage: Less chance of damaging I.A.N
Disadvantage : Decreased skeletal stability

21. Straight line incision
Mandibular foramen approx 1
cm from posterior ramus.

22. Oscillating Blade Standard
thickness(1mm)
a)Short ( 7mm)
b) Long (12mm)

23. Outline of IVRO cut
A) Setback upto 4mm B) Setback =/> 5mm

24. A) Superior osteotoy : Shank parallel to
mand. Occlusal plane
B) Inferior OsteotomyShank
divergent to mand. Occlusal plane

25. Panoramic radiograph after Lefort I
and IVRO

26. High to low wiring

27. A) IVRO ( vertical stripping of medial
pterygoid muscle )
B) Modified condylotomy -
horizontal stripping of medial
pterygoid muscle .

28. ALTERNATE TECHNIQUE
Extra oral technique:
Incision: 4cm incision 2cm below
the angle of mandible
Indications: for large mandibular
setbacks of greater than 10mm
Advantage: Better access
Disadvantage: Scar formation

29. INVERTED L & C RAMUS OSTEOTOMIES
Trauner and Obwegeser in 1957
Indications: Horizontal
mandibular excess/deficiencies.
Incision: 6cm submandibular
incision 2cm below the angle &
inferior border of mandible
Exposure: entire ramus

30. Inverted L–Osteotomy views

31. ALTERNATE TECHNIQUES FOR
INVERTED L OSTEOTOMIES [C –
osteotomy]
Advantage :
To increase
the bone
contact
during
advancement

32. To increase bone contact&
to prevent notching
To increase bone contact
& improve bone healing-
bone graft placement

33. BILATERAL
SAGITTAL SPLIT
OSTEOTOMY
Indications: Every
possible movement that
includes the entire
horizontal ramus of the
mandible.
Incision: given on the
anterior portion of vertical
ramus, midway between
the occlusal planes & is
carried down through the
middle of the retromolar
fossa to a point about
5mm behind the 2nd
molar.

34.  Dalpoints modification (1961)
 Advantage: Easy splitting
 Obwegeser original:
 Obwegeser modified

35. Dal pont in 1961,lower horizontal cut to a vertical
cut.
Hunsuck in1968,shorter horizontal cut just
posterior to lingula.

36. Soft Tissue incision
 Subperiosteal
dissection

37. Visualization of lingula can be improved of convex
internal oblique ridge

38. Horizontal ramus osteotomy parallel to occlusal
plane.
Osteotomy should be carried posterior to lingula.

39. Incase of setbacks, small segment of bone should be
removed superior to horizonatal osteotomy high
occlusal plane angles.

40. Buccal osteotomy
 Include the lingual
cortex in the buccal
osteotomy at inferior

41. Drill holes for holding wires

42. Splitting of mandible

43. Small sagital split separotor is placed deep
into
buccal osteotomy.

44. Osteotomes used to
split

45. Smith spreader
Used to split the
cortex

46. Nurovascular bundle attached to
proximal segment.

47. Fracture of buccal cortex of mandibular
body.

48. Seperated bucal cortex replaced
and secured with screws.

49. Fracture of buccal cortex involving
body and ramus

50. Fracture of vertical osteotomy on medial
aspect of ramus anterior to inferior alveolar
foramen

51. Fracture of retromolar segment of
mandible distal to second molar.

52. Stripping of
pterygomasseteric
sling
 Stripping of medial pterygoid
muscle and stylomandibular
ligament on medial aspect, in
case of mandibular setback

53. Mobilization of distal segment.

54. Condylar positioning

55. Drilling holes for bicortical screws

56. Bicortical screws Vs Lag screws

57. HORIZONTAL BODY OSTEOTOMIES
INDICATIONS:
Prognathism
Incision: is made 4-5mm
below the level of attached
gingiva & is carried forward at
this level until the canine,
where it can be dropped
down 5mm & extended
forward to the midline.

58. SUBAPICAL OSTEOTOMIES
Anterior subapical
Posterior subapical
Total alveolar osteotomy

59. ANTERIOR SUBAPICAL OSTEOTOMY
Indications: To move the anterior
mandible in every desirable
direction[ant,post,sup,inf-
repositioning]
Incision : is started 1cm behind
the planned vertical osteotomy&
is carried 4-5mm below the
attached gingiva & is brought to
the midline & connected with the
opposing incision.

60. POSTERIOR SUBAPICAL
OSTEOTOMY
Correction of supraeruption of
posterior mandibular teeth.
Ankylosis of some posterior
teeth.
Abnormal buccal/lingual
position of teeth.
Incision is made at the anterior
border of vertical ramus & is
carried forward to the canine

61. TOTAL ALVEOLAR OSTEOTOMY
Indications: Mandibular
protrusion, mandibular
retrusion, anterior open bite
when used with a bone graft.
Incision: Started on the
external oblique ridge of the
base of the vertical ramus 4-
5mm below the attached
gingiva & carried forward to the
canine & is connected to the
contralateral incision

63. ALTERNATE TECHNIQUE-TOTAL ALVEOLAR
OSTEOTOMY - Dalpont (1961)
Total alvoelar osteotomy+
Sagittal split osteotomy of
vertical ramus.
ADVANTAGES:
Osteotomy made below
the inferior alveolar nerve
there by decreasing the
risk of damaging the IAN
,apices of the teeth &
preserving vascular
supply to the mobile
segment, also sagittal
part allows a larger bone
contact area to assist in
healing.

64. SOFT TISSUE CHANGES INDUCED BY SURGERY
Advancement of the mandible :
 Increase in lower lip protrusion, chin prominence.
 Enhanced chin neck definition.
 Decreased prominence of labiomental fold.
 Decreased lower lip eversion.
 Increased lower third facial height.

65. Total subapical surgery for dentoalveolar horizontal
deficiency:
Increased lower lip prominence, Increased lower facial
height, decreased depth of labiomental fold.
Correction of Mandibular horizontal excess:
Reduced chin prominence & lower lip eversion,
decreased lower facial height, increased prominence of
angles.
Excessive setbacks in older & obese individuals:
Increased fullness in the submental region & produce
poor chin & neck contour.

66. GENIOPLASTIES
Hofer (1942) , Converse (1950) , Trauner & Obwegeser
(1957)
Genioplasty can be used as a single procedure or it can be
used as an adjunctive procedure along with other major
osteomies of the jaw bone.
Deformities of the chin should be considered in all 3
planes:
AP
Vertical
Transverse
It can be used to augment, reduce, straighten or lengthen
the chin.

67. Augmentation Genioplasty
Used to increase the chin
projection.
Sliding horizontal osteotomy
of the symphysis region.
Autogenous bone graft
Alloplastic material –
silastic, hydroxyapatite.

68. Reduction Genioplasty
Reduction of the
symphysis region
can be achieved
both in the
anteroposterior
and vertical planes
or in both planes
depending on the
need of the patient.

69. Straightening Genioplasty Procedure
Indication:
• In Facial asymmetry, where the
complete correction of the asymmetry
cannot be achieved by appropriate
jaw osteotomies. E.g., TM joint
ankylosis.
• The horizontal osteotomy is done and
segment Is shifted laterally and than
contoured to get desired result.

70. Mucosal and submucosal incision and
subperiosteal dissection

71. Establish refrence points
 Hole for the
positioning wire

72. Osteotomy Design

73. Chin osteotomy and mobilization

74. Chin Repositioning and Tricortical
screw placement
Counter sink hole

75. Bone plate fixation

76. Double Sliding Genioplasty

77. Anteroposterior Chin Reduction

78. Vertical increase of Chin

79. Correction of Chin Asymmetry
(Propeller Osteotomy)

80. Widening/Narrowing
of Posterior Chin
dimension
Narrowing of
Anterior Chin
dimension
Widening of
Anterior Chin
dimension

81. Suturing of Submucosal and mucosal
tissue layers

82. Tennon Technique (Michelet –
1974)

83. dimensional reduction genioplasty. Keyhan
SO, Khiabani K, Hemmat S, Varedi P , Br J Oral
Maxillofac Surg.2013]